3,295 research outputs found
Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian
We study the semi-classical motion of holes by exact numerical solution of
the Luttinger model. The trajectories obtained for the heavy and light holes
agree well with the higher order corrections to the abelian and the non-abelian
adiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378(2003)],
respectively. It is found that the hole trajectories contain rapid oscillations
reminiscent of the "Zitterbewegung" of relativistic electrons. We also comment
on the non-conservation of helicity of the light holes.Comment: 4 pages, 5 fugure
Thermodynamics of spin-1/2 tetrameric Heisenberg antiferromagnetic chain
The thermodynamic properties of a spin S=1/2 tetrameric Heisenberg
antiferromagnetic chain with alternating interactions AF1-AF2-AF1-F (AF and F
denote the antiferromagnetic and ferromagnetic couplings, respectively) are
studied by means of the transfer-matrix renormalization group method and
Jordan-Wigner transformation. It is found that in the absence of magnetic
field, the thermodynamic behaviors are closely related to the gapped low-lying
excitations, and a novel structure with three peaks in the temperature
dependence of specific heat is unveiled. In a magnetic field, a phase diagram
in the temperature-field plane for the couplings satisfying JAF1=JAF2=JF is
obtained, in which various phases are identified. The temperature dependence of
thermodynamic quantities including the magnetization, susceptibility and
specific heat are studied to characterize the corresponding phases. It is
disclosed that the magnetization has a crossover behavior at low temperature in
the Luttinger liquid phase, which is shown falling into the same class as that
in the S=1 Haldane chain. In the plateau regime, the thermodynamic behaviors
alter at a certain field, which results from the crossing of two excitation
spectra. By means of the fermion mapping, it is uncovered that the system has
four spectra from fermion and hole excitations that are responsible for the
observed thermodynamic behaviors.Comment: 10 pages, 10 figures, accepted by Phys. Rev.
Antiferromagnetism and hole pair checkerboard in the vortex state of high Tc superconductors
We propose a microscopic state for the vortex phase of BSCO superconductors.
Around the vortex core or above H_{c2}, the d wave hole pairs form a
checkerboard localized in the commensurate antiferromagnetic background. We
discuss this theory in connection with recent STM experiments.Comment: Final versio
The cosmological origin of Higgs particles
A proposal of the cosmological origin of Higgs particles is given. We show,
that the Higgs field could be created from the vacuum quantum conformal
fluctuation of Anti-de Sitter space-time, the spontaneous breaking of vacuum
symmetry, and the mass of Higgs particle are related to the cosmological
constant of our universe,especially the theoretical estimated mass m of
Higgs particles is m =.Comment: 7 pages,no figure
A new approach to bulk viscosity in strange quark matter at high densities
A new method is proposed to compute the bulk viscosity in strange quark
matter at high densities. Using the method it is straightforward to prove that
the bulk viscosity is positive definite, which is not so easy to accomplish in
other approaches especially for multi-component fluids like strange quark
matter with light up and down quarks and massive strange quarks.Comment: 7pages, talk given in SQM2008. Minor revisions, including
clarification and updated reference
A practical synthesis of a novel DPAGT1 inhibitor, aminouridyl phenoxypiperidinbenzyl butanamide (APPB) for in vivo studies
Immunotherapy that targets N-linked glycans has not yet been developed due in large part to the lack of specificity of N-linked glycans between normal and malignant cells. N-Glycan chains are synthesized by the sequential action of glycosyl transferases in the Golgi apparatus. It is an overwhelming task to discover drug-like inhibitors of glycosyl transferases that block the synthesis of specific branching processes in cancer cells, killing tumor cells selectively. It has long been known that N-glycan biosynthesis can be inhibited by disruption of the first committed enzyme, dolichyl-phosphate N-acetylglucosaminephosphotransferase 1 (DPAGT1). Selective DPAGT1 inhibitors have the promising therapeutic potential for certain solid cancers that require increased branching of N-linked glycans in their growth progressions. Recently, we discovered that an anti-Clostridium difficile molecule, aminouridyl phenoxypiperidinbenzyl butanamide (APPB) showed DPAGT1 inhibitory activity with the IC_(50) value of 0.25 μM. It was confirmed that APPB inhibits N-glycosylation of β-catenin at 2.5 nM concentration. A sharp difference between APPB and tunicamycin was that the hemolytic activity of APPB is significantly attenuated (IC_(50) > 200 μM RBC). Water solubility of APPB is >350-times greater than that of tunicamycin (78.8 mg/mL for APPB, 60 min) for in vivo studies (PK/PD, safety profiles, and in vivo efficacy) using animal models. We have refined all steps in the previously reported synthesis for APPB for larger-scale. This article summarizes protocols of gram-scale synthesis of APPB and its physicochemical data, and a convenient DPAGT1 assay
Topological insulators and superconductors
Topological insulators are new states of quantum matter which can not be
adiabatically connected to conventional insulators and semiconductors. They are
characterized by a full insulating gap in the bulk and gapless edge or surface
states which are protected by time-reversal symmetry. These topological
materials have been theoretically predicted and experimentally observed in a
variety of systems, including HgTe quantum wells, BiSb alloys, and BiTe
and BiSe crystals. We review theoretical models, materials properties
and experimental results on two-dimensional and three-dimensional topological
insulators, and discuss both the topological band theory and the topological
field theory. Topological superconductors have a full pairing gap in the bulk
and gapless surface states consisting of Majorana fermions. We review the
theory of topological superconductors in close analogy to the theory of
topological insulators.Comment: 55 pages, 44 figures, Review article commissioned by the Review of
Modern Physics. Please help us to improve the article by emailing us your
comments and missing reference
Universal Fluctuation of the Hall Conductance in the Random Magnetic Field
We show that the RMS fluctuation of the antisymmetric part of the Hall
conductance of a planar mesoscopic metal in a random magnetic field with zero
average is universal, of the order of , independent of the amplitude of
the random magnetic field and the diffusion coefficient even in the weak field
limit. This quantity is exactly zero in the case of ordinary scalar disorder.
We propose an experiment to measure this surprising effect, and also discuss
its implications on the localization physics of this system. Our result applies
to some other systems with broken time-reversal ({\bf T}) symmetry.Comment: 4 pages, Revtex 3.0; added the paragraph regarding applicability to
other systems with broken T-invariance, misc. minor change
Critical phenomena in disc-percolation model and its application to relativistic heavy ion collisions
Through studying the critical phenomena in continuum-percolation of discs, we
find a new approach to locate the critical point, i.e. using the inflection
point of as an evaluation of the percolation threshold. The
susceptibility, defined as the derivative of , possess finite-size
scaling property, where the scaling exponent is the reciprocal of -- the
critical exponent of correlation length. The possible application of this
approach to the study of the critical phenomena in relativistic heavy ion
collisions is discussed. The critical point for deconfinement can be extracted
by the inflection point of -- the probability for the event with
QGP formation. The finite-size scaling of its derivative can give the critical
exponent , which is a rare case that can provide an experimental measure
of a critical exponent in heavy ion collisions.Comment: 5 pages, 7 figure
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